FIG. 10 shows the interior of railroad vehicles wherein seats 8 elongated in the direction of advance of the vehicle and entrance-exit doors 84 are arranged alternately along both side walls of the vehicle. When the floor of the vehicle is to be automatically cleaned by a robot having rotary brushes or like cleaning means, the robot must be caused to automatically travel along a predetermined course. The travel needs to cover every nook and corner while avoiding obstacles such as the seats 8.
Such railroad vehicles are generally divided into two types, i.e., motor (engine) cars (FIG. 10, (a)) having a driver's (engineer's) cab 85 at the front or rear end with respect to the direction of advance, and passenger cars (FIG. 10, (c)) having no driver's cab and having seats 8 including those positioned at the front and rear ends. The path of travel of the robot needs to be changed according to the type of vehicles to be cleaned.
For use in conventional automatic locomotion robots, a control system is already known which comprises visual sensors mounted on the body of the robot as directed outside therearound for controlling the travel of the robot while recognizing obstacles based on the outputs of the visual sensors.
When used for the floor cleaning robot, the system visually detects the presence of the seat 8 or driver's cab 85, enabling the robot to travel automatically on the floor.
However, the conventional system must monitor the outputs of the visual sensors at all times to detect presence or absence of obstacles and judge the configuration of the obstacle, if any, such that every time an obstacle has been detected, the system needs to make a decision as to the course of travel to avoid the obstacle. Accordingly, even if a microcomputer is used for making the judgment and decision, a very complex procedure needs to be executed.
Consequently, the robot must discontinue its travel for a long period of time when changing the direction of advance. The system is therefore unusable for the floor cleaning robot.
On the other hand, it appears useful to move the robot along a predetermined course of travel stored in the robot in advance. In this case, however, it becomes necessary not only to set a plurality of courses of travel for different types of vehicles and to follow an input procedure for a change-over between the courses but also to set the robot in a predetermined initial position accurately, whereas errors will invariably occur in positioning the robot, or the actual path traveled by the robot will inevitably involve a deviation from the predetermined course, for example, owing to slippage of the travel mechanism which occurs subsequently. Such errors, if accumulating, will greatly deviate the robot from the predetermined course.